"People need to understand just how radical a departure this is from the mean of American politics," Schmidt said.

Back in 2008, Schmidt was McCain's chief strategist. That year, McCain said, "We need to know the full extent of Senator Obama's relationship with ACORN, who is now on the verge of maybe perpetrating one of the greatest frauds in voter history in this country, maybe destroying the fabric of democracy."

McCain made the comments about then-presidential candidate Obama's connections to ACORN during a debate with Obama, in which Obama refuted McCain's claims.

Conservative activists' targeting of ACORN appeared to be successful. They released undercover video footage that purported to show illegal activity by ACORN staff. The Los Angeles Times reported that Congress passed Republican-backed amendments that stripped funding from the group, leading to its shutdown in 2010.

Today, Trump is bringing up the possibility of voter fraud again. A New York Times report suggested that Trump's comments have taken on a tone of racial unrest.

"It went from being laughable to be what I consider to be dangerous," UC Irvine election law expert Richard L. Hasen told The Times.

After losing the election to Obama, McCain returned to the Senate. He is running for reelection, but might be facing the "Trump Effect," in which Trump's remarks appear to cause damage to Republicans down the ballot.